netdev - Re: [PATCH 2/3] enic: add main netdev file withmoduleinfrastructure

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Message-Id: <1221678230.3244.101.camel@achroite>
Date:	Wed, 17 Sep 2008 20:03:49 +0100
From:	Ben Hutchings <bhutchings@...arflare.com>
To:	Scott Feldman <scofeldm@...co.com>
Cc:	netdev@...r.kernel.org
Subject: Re: [PATCH 2/3] enic: add main netdev file withmoduleinfrastructure

On Wed, 2008-09-17 at 11:51 -0700, Scott Feldman wrote:
> On Wed, 17 Sep 2008, Ben Hutchings wrote:
> 
> > On Tue, 2008-09-16 at 18:49 -0700, Scott Feldman wrote:
> >>>> +static void enic_notify_timer(unsigned long data)
> >>>> +{
> >>>> +	struct enic *enic = (struct enic *)data;
> >>>> +
> >>>> +	enic_notify_check(enic);
> >>>> +
> >>>> +	mod_timer(&enic->notify_timer, round_jiffies(ENIC_NOTIFY_TIMER_PERIOD));
> >>>
> >>> You want round_jiffies_relative() not round_jiffies().
> >>
> >> No, I want round_jiffies().
> > [...]
> >
> > The kernel-doc says:
> > "round_jiffies() rounds an absolute time in the future (in jiffies)
> > up or down to (approximately) full seconds. This is useful for timers
> > for which the exact time they fire does not matter too much, as long as
> > they fire approximately every X seconds."
> >
> > You're passing in ENIC_NOTIFY_TIMER_PERIOD which is a relative time.
> 
> I tried both and round_jiffies(2) gave the desired result of calling the timer
> every two seconds.  Using round_jiffies_relative(2) called the timer
> continuously.

Sorry, yes, round_jiffies_relative() not only takes but also returns a
relative time - which if interpreted as absolute is always in the past.
So calling round_jiffies() is right, but the argument should be jiffies
+ ENIC_NOTIFY_TIMER_PERIOD.

Ben.

-- 
Ben Hutchings, Senior Software Engineer, Solarflare Communications
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.

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